for /f %%e in ('findstr "<cd_comiss>P</cd_comiss>" *.*') do del %%e

for /f %e in ('findstr "<cd_comiss>P</cd_comiss>" *.*') do del %e

Apaga todos os arquivos com a string, menos o próprio Bat, use filtro:
   |findstr /vilc:"%~0"
Ou, Apaga todos os arquivos com a string, menos o próprio Bat, use filtro:
   |findstr /vilc:".cmd"

for /f %%e in ('findstr "^<cd_comiss^>P^</cd_comiss^>" *.xml^|findstr /vilc:"*.cmd"')do echo/del %%e

@echo off && setlocal enableextensions enabledelayedexpansion & echo/

echo/ & title <nul & title Q213311 & mode 100,10 & set "_str="^< cd_comiss^>P^< /cd_comiss^>"" & echo/
for /f %%c in ('copy /Z "%~dpf0" nul')do set "_cr=%%c" & for /f %%a in ('"prompt $H&for %%b in (0) do rem"')do set "_bs=%%a"

for /f %%f in ('where /r . "*.*"^|findstr /vilc:"%~0"')do for /f ^tokens^=^*delims^=^  %%E in ('type %%f^|findstr /ilm !_str!')do (
     ping -n 2 -4 127.0 >nul & echo/ !_cr! & del /q /f "%%~f" >nul && <nul set /p"^=!_bs!!_cr! ^|Arquivo:^| "%%~f" ^| Apagado^!!"
    )